Technical Field
Embodiments described herein relate to displays, and more particularly, to performing synchronous backlight updates on a display.
Description of the Related Art
Part of the operation of many computer systems, including portable digital devices such as mobile phones, notebook computers and the like, is the use of some type of display device, such as a liquid crystal display (LCD), to display images, video information/streams, and data. Accordingly, these systems typically incorporate functionality for generating images and data, including video information, which are subsequently output to the display device. Such devices typically include video graphics circuitry to process images and video information for subsequent display.
In digital imaging, the smallest item of information in an image is called a “picture element”, more generally referred to as a “pixel.” For convenience, pixels are generally arranged in a regular two-dimensional grid. By using this arrangement, many common operations can be implemented by uniformly applying the same operation to each pixel independently. Since each pixel is an elemental part of a digital image, a greater number of pixels can provide a more accurate representation of the digital image. To represent a specific color on an electronic display, each pixel may have three values, one each for the amounts of red, green, and blue present in the desired color. Some formats for electronic displays may also include a fourth value, called alpha, which represents the transparency of the pixel. This format is commonly referred to as ARGB or RGBA. Another format for representing pixel color is YCbCr, where Y corresponds to the luma, or brightness, of a pixel and Cb and Cr correspond to two color-difference chrominance components, representing the blue-difference (Cb) and red-difference (Cr).
Most images and video information displayed on display devices such as LCD screens are interpreted as a succession of image frames, or frames for short. While generally a frame is one of the many still images that make up a complete moving picture or video stream, a frame can also be interpreted more broadly as simply a still image displayed on a digital (discrete, or progressive scan) display. A frame typically consists of a specified number of pixels according to the resolution of the image/video frame. Most graphics systems use frame buffers to store the pixels for image and video frame information.
Often, the primary draw of battery power of a portable device is the display device and, in particular, the backlight, which can be used to illuminate the display device. The backlight may provide a background light or color over which text, pictures and/or images are displayed. Displays with backlights (e.g., LCDs) are widely used in mobile devices and provide excellent viewing indoors. However, when used outside, ambient light may reflect off the surface of the display, thereby making it difficult to view the display in high ambient light conditions. Accordingly, techniques for adjusting the backlight are needed in response to changes in the viewing environment to provide for optimal viewing conditions for the user.